EP3148812B1

EP3148812B1 - Shroud for a printhead assembly module and printhead assembly module

Info

Publication number: EP3148812B1
Application number: EP14893601.6A
Authority: EP
Inventors: Ronald J. Ender; Daniel D. Dowell
Original assignee: Hewlett Packard Development Co LP
Current assignee: Hewlett Packard Development Co LP
Priority date: 2014-05-30
Filing date: 2014-05-30
Publication date: 2020-12-23
Anticipated expiration: 2034-05-30
Also published as: US10618288B2; US20180236772A1; WO2015183317A1; EP3148812A1; US9975339B2; US20170087847A1; CN106414084A; CN106414084B; EP3148812A4

Description

BACKGROUND

In some Inkjet printers, a stationary media wide printhead assembly, commonly called a print bar, is used to print on paper or other print media moved past the print bar.
US 2011/011 5848 describes fluid injecting apparatus comprising projecting portions formed on an attachment plate of a printing head unit. The projecting portions form an absorbing member accommodating portion, such that an absorbing member does not protrude from the absorbing member accommodating portion.
US 2010/ 0053265 A1 relates to an array type inkjet print head with a flat plate cover having openings corresponding to print head chips.
WO2014/003727 A1 discloses a shroud for protecting the printheads in a print bar employing bumps to guide the leading edge of print media away from the printheads during printing when the shroud is affixed to print bar.
US2005/200669 A1 relates to a printhead cover with at least one barrier provided for preventing the adhesive material used for printhead connectors from spreading away. JPH05338160 relates to shroud structure for a printhead that protects nozzle surfaces during printing and wiping.

DRAWINGS

Fig. 1 is a block diagram illustrating an Inkjet printer in which examples of a new printhead assembly shroud may be implemented.
Fig. 2 illustrates a modular print bar implementing one example of a protective shroud such as might be used in the printer of Fig. 1.
Fig. 3 is a perspective view of one of the printhead assembly modules in the print bar shown in Fig. 2.
Fig. 4 is an exploded view of the printhead assembly module shown in Fig. 3.
Fig. 5 is a close up view showing the topography of the shroud in the module of Figs. 3 and 4 in more detail.
Fig. 6 is a section along the line 6-6 in Fig. 5.
Fig. 7 is a detail view from Fig. 6.
Fig. 8 is a section view along the line 8-8 in Fig. 5.
Fig. 9 is a side view illustrating one example print zone in an Inkjet printer implementing the printhead assembly shroud shown in Figs. 2-8.
Figs. 10 and 11 illustrate other examples of a new printhead assembly shroud.

The same part numbers designate the same or similar parts throughout the figures. The figures are not necessarily to scale. The size of some parts may be exaggerated for clarity.

DESCRIPTION

A stationary print bar in an inkjet printer is susceptible to print quality defects and damage from paper or other print media contacting into the printheads. Fragile parts in the print bar can also be damaged during handling, for example during shipping and installation. A protective shroud is sometimes used to protect the printheads and other fragile components in the print bar. A new modular print bar with "stackable" (horizontally end-to-end), interchangeable printhead assembly modules is disclosed in publication WO2015183309 titled Printhead Assembly Module. The new modular print bar has been developed for use in large format inkjet printers to expand the range of media sizes that may be printed with a stationary media wide print bar. The use of interchangeable printhead assembly modules, however, may increase handling and the corresponding risk of damage. Also, the arrangement of the printheads on the new modules broadens the area covered by the shroud compared to existing printhead assemblies. Accordingly, a new, more robust shroud has been developed to better protect the printheads and other fragile parts during handling and printing.
In one example, a printhead assembly shroud includes openings through which the printheads are exposed and a ridge or other elongated protrusion along an exterior surface next to the openings. The elongated protrusion helps block the print media and other intrusions from contacting the exposed part of the printheads as well as strengthens the body of the shroud covering the periphery of the printheads and other parts of the printhead assembly.
In one example for an interchangeable printhead module such as that disclosed in WO2015183309 the shroud includes a first group of openings aligned across the shroud body and a second group of openings aligned across the body behind and parallel to the first group of openings. Each opening surrounds an exposed part of a printhead. A first ridge protrudes from and extends across the body in front of the first group of openings and a second ridge protrudes from and extends across the body in front of the second group of openings. The first and second groups of openings are symmetrical with respect to one another about an axis of symmetry and the first and second ridges are symmetrical with respect to one another about the axis such that the shroud is reversible between two orientations to protect the printheads with the first ridge in front of the openings or with the second ridge in front of the openings.
Examples of the new shroud are described with reference to printhead assembly modules that may be used in a stationary media wide print bar. However, examples of the new shroud are not limited to media wide print bars, printhead assembly modules, or even inkjet printers, but might also be implemented with other print mechanisms and in other inkjet type dispensers. The examples shown and described, therefore, illustrate but do not limit the disclosure, which is defined in the Claims following this Description.
Fig. 1 is a block diagram illustrating an inkjet printer 10 in which examples of a new printhead assembly shroud 12 may be implemented. Referring to Fig. 1, printer 10 includes a print bar 14 with an arrangement of printheads for dispensing ink or other printing fluid on to a sheet or continuous web of paper or other print media 16. Printer 10 also includes a print media transport mechanism 18 for moving media 16 past print bar 14, as indicated by direction arrows 19, printing fluid supplies 20 for supplying printing fluid to print bar 14, and a printer controller 22. Controller 22 represents generally the programming, processor(s) and associated memories, and the electronic circuitry and components needed to control the operative elements of printer 10. As described in detail below with reference to the example shown in Figs. 2-9, shroud 12 includes ridges or other topography 24 to strengthen shroud 12 and to help block media 16 and other intrusions from contacting the printheads and other parts of print bar 14.
Fig. 2 illustrates a modular print bar 14 implementing one example of a protective shroud 12 such as might be used in a printer 10 shown in Fig. 1. Fig. 3 is a perspective view of one of the printhead assembly modules 26 in print bar 14 shown in Fig. 2. Fig. 4 is an exploded view of printhead assembly module 26. Referring to Figs. 2-4, print bar 14 includes identical printhead assembly modules 26 arranged end-to-end so that a protruding end of one module 26 overlaps a protruding end of the adjacent module. Thus, multiple interchangeable modules 26 are "stacked" end-to-end to form print bar 14.
Each module 26 includes printheads 28A-28F mounted to a chassis 30 and surrounded by shroud 12. In addition to supporting printheads 28A-28F and shroud 12, chassis 30 may provide the structural support and reference surfaces for accurately mounting print bar 14 in a printer. Chassis 30 usually will also house a part of the flow path for supplying printing fluid to each printhead 28A-28F including, for example, a series of channels 32 visible in Fig. 4. Although two modules 26 each with six printheads 28A-28F in a staggered arrangement are shown, other configurations are possible. For example, more modules with more or fewer printheads could be used and with the printheads arranged differently from that shown.
Fig. 5 is a close up view showing the topography of shroud 12 in more detail. Figs. 6 and 8 are sections from Fig. 5 and Fig. 7 is a detail from Fig. 6. The sections of Figs. 6 and 8 are re-oriented (flipped over) from the view lines in Fig. 5 to depict the shroud topography protruding downward consistent with the perspectives of Figs. 3 and 4. Referring to Figs. 5-8, in the example shown, shroud 12 includes a body 34 having a perimeter 36 that conforms to the perimeter of chassis 30 in a generally stretched S shape characterized by elongated, parallel parts 38, 40 staggered relative to one another with protruding ends 42, 44.
Each printhead 28A-28F is exposed through an opening 54A-54F in shroud body 34 to dispense printing fluid past shroud 12 onto the print media. In the example shown, each opening 54A-54F completely surrounds the exposed part of a corresponding printhead 28A-28F. Also in the example shown, printheads 28A-28F are arranged on printhead assembly module 26 in two rows in a staggered configuration in which the end of each printhead overlaps the end of the adjacent printhead(s). Accordingly, the openings in shroud body 34 are arranged into a first group 56 (openings 54A-54C) aligned across a first, upstream side 58 of body 34 and a second group 60 (openings 54D-54F) aligned across a second, downstream side 62 of body 34 parallel to the openings in first group 56. In this context, "upstream" and "downstream" are taken with respect to the direction print media 16 moves past printhead assembly modules 26, as indicated by direction arrows 19 in Figs. 1 and 9.
Continuing to refer to Figs. 5-8, shroud 12 includes a ridge 64 that extends across body 34 in front of the upstream group 56 of openings 54A-54C to block print media from contacting printheads 28A-28C. In the example shown, shroud 12 includes a ridge 66 that extends across body 34 behind the downstream group 60 of openings 54D-54F, mirroring front ridge 64 so that each shroud 12 (and printhead assembly module 26) is reversible between two orientations, with either side 58 or side 62 facing upstream in the print media direction 19 (Figs. 1 and 9). Ridges 64 and 66 together completely span all openings 54A-54F and, correspondingly, the exposed part of all printheads 24A-24F when shroud 12 is installed on the printhead assembly.
In the example shown, mirrored ridges 68, 70 snake along each end 42, 44 of shroud body 34. End ridges 68, 70 help protect against print media contacting printheads 28D-28F during printing or inadvertent contact during handling. Also, in the example shown, ridges 68, 70 are discontinuous to provide lanes 72, 74 to facilitate wiping the printheads during servicing operations. Shroud 12 may include a ridge 76 extends across body 34 between each group 56, 60 of openings 54A-54C, 54D-54F parallel to front ridge 64 and rear ridge 66 to help block print media from contacting the exposed part of printheads 28D-28F. Ridge 76 also stiffens shroud body 34 in the otherwise flat interior area of body 34.
Shroud 12 may include ramps 82 protruding from body 34 to help support module 26 and protect the printheads, for example if the module is placed on a surface with the printheads facing down. Each ramp 82 is configured as a two sided ramp positioned between laterally adjacent openings in each group 56, 60. Dual inclines 84, 86 slope in the direction a wiper moves back and forth across the printheads so the wipers do not encounter abrupt bumps during printhead wiping. Each ramp 82 is also sloped in the print media direction, as best seen in the section of Fig. 6, to not present an abrupt edge to any print media that might contact the middle areas of shroud 12 and to facilitate cleaning residue and debris that may accumulate between the protrusions.
Ridges 64-70 and 76 and ramps 82 may be embossed or otherwise formed as an integral part of shroud body 34 or as discrete parts affixed to shroud body 34. Ridges 64 and 66 are spaced apart from openings 54A-54F to allow a substantially flat surface 88 completely surrounding openings 54A-54F. Surface 88 forms a contiguous part of the exterior surface of the shroud body 34 completely surrounding all of the openings 54A-54F inside a perimeter of ridges 64 and 66. A cap is a pressed against surface 88 to seal off the exposed printheads to help keep air from drying out ink in the printhead nozzles during periods of inactivity. While the width of "capping" surface 88 may vary depending on the particular capping device and sealing requirements, it is expected that a capping surface width of at least 0.40mm will usually be desired for an adequate seal.
As best seen in the detail of Fig. 7, each printhead 28A-28F protrudes from shroud body 34 a distance D1 and each ridge 64-70 and 76 protrudes from shroud body 34 a greater distance D2. A larger D2 (compared to D1) offers better protection for the printheads, however it is usually desirable to have very small printhead-to-media spacing for good print quality. Accordingly, it usually will be desirable to keep D2 as small as possible. While the difference between D2 and D1 may vary, for example depending on the type of print media and the desired printhead-to-media spacing, it is expected that a difference of at least 0.10mm will be adequate for many large format printing applications.
In Fig. 9, a print bar 14 with a printhead assembly module 26 is positioned over a printer's media support platen 78 defining a print zone 80 in which printing fluid is dispensed on to the paper or other print media 16. Media transport 18 (Fig. 1) includes print zone entry rollers 90, 92 and exit rollers 94, 96. As noted above, ridges 64-70 and 76 (Figs. 5-8) individually and together block a leading edge of media 16 from crashing into the exposed part of the printheads and help hold print media 16 away from the printheads, for example to block any wrinkles or buckles in media 16 from contacting the printheads.
It may not be desirable in all implementations for a shroud 12 to include all of the features shown in Figs. 2-9. For example, shroud 12 may include only perimeter ridges 64, 68 and 70 as shown in Fig. 10. In another example, shroud 12 may include only a center ridge 76 and ramps 82 as shown in Fig. 11.

Claims

A shroud (12) to protect a group of printheads (28) in a printhead assembly module (26), the module (26) being formed with an extended S shape such that, when stacked end to end to form a print bar, a protruding end of one module (26) overlaps a protruding end of the adjacent module, the shroud (12) having a perimeter that conforms to the perimeter of the module (26) and comprising openings (54) through which the printheads are exposed when the shroud (12) is installed on the printhead assembly,
characterized in that the shroud is also comprising an elongated protrusion (64, 66) along an exterior surface next to the openings (54) and end ridges (68, 70) which snake along each end of the exterior surface of the shroud (12), wherein the elongated protrusion (66, 66) and the end ridges (68, 70) are arranged to block print media (16) from contacting the exposed part of the printheads (28) during printing when the shroud (12) is installed on the printhead assembly.
The shroud (12) of Claim 1, wherein the protrusion includes a continuous elongated protrusion in front of the openings.
The shroud (12) of Claim 1, wherein the protrusion includes multiple ridges (68, 70) each located laterally next to an opening (54) and spanning a length of the opening (54).
The shroud (12) of Claim 1, wherein the protrusion completely spans all of the openings (54).
The shroud (12) of Claim 4, wherein the protrusion spanning all of the openings (54) includes multiple ridges (68, 70) that together completely span all of the openings (54).
The shroud (12) of Claim 4, wherein the protrusion spanning all of the openings (54) includes a ridge (64, 66, 68, 70, 76) in front of each opening with respect to a direction in which print media (16) is intended to move past the printhead assembly module (26), and a ridge (64, 66, 68, 70, 76) behind each opening with respect to a direction in which print media (16) is intended to move past printhead assembly module (26).
The shroud (12) of Claim 5, further comprising a contiguous part of the exterior surface completely surrounding all of the openings (54) inside a perimeter of the ridges (68, 70).
The shroud (12) of Claim 1, further comprising a ramp (82) protruding from the exterior surface between laterally adjacent openings (54), each ramp (82) having two, opposing inclines extending away from one another in a direction parallel to a direction a wiper moves across the printheads when the shroud (12) is installed on the printhead assembly.
The shroud (12) of claim 1 further comprising a shroud body (34);
a first group of openings aligned across the shroud body and a second group of openings aligned across the shroud body behind and parallel to the first group of openings, each opening (54) surrounding an exposed part of a printhead (28) when the shroud (12) is installed on the printhead assembly; and wherein
the elongate protrusion (64, 66) comprises a first ridge (64, 66) protruding from and extending across the body in front of the first group of openings (54) with respect to a direction in which print media (16) is intended to move past the printhead assembly module (26) and the shroud (12) further comprises a second ridge (76) protruding from and extending across the shroud body in front of the second group of openings with respect to a direction in which print media (16) is intended to move past the printhead assembly module (26).
The shroud (12) of Claim 9, wherein the first and second groups of openings (54) are symmetrical with one another about an axis and the first and second ridges (68, 70) are symmetrical with one another about the axis such that the shroud (12) is reversible between two orientations to protect the printheads with the first ridge (64, 66) in front of the openings or with the second ridge (76) in front of the openings.
The shroud (12) of Claim 9, further comprising a third ridge (64, 66) protruding from and extending across the body behind the second group of openings (54) with respect to a direction in which print media (16) is intended to move past the printhead assembly module (26).
The shroud (12) of Claim 11, wherein the first ridge (64, 66) includes a single uninterrupted ridge completely spanning the first group of openings (54) and the third ridge (64, 66) includes a single uninterrupted ridge completely spanning the second group of openings (56).
The shroud (12) of Claim 9, further comprising a ramp (82) protruding from the shroud body (34) between each pair of laterally adjacent openings, each ramp (82) having two, opposing inclines extending laterally away from one another.
A printhead assembly module (26), the module (26) being formed with an extended S shape such that, when stacked end to end to form a print bar, a protruding end of one module (26) overlaps a protruding end of the adjacent module, comprising:
multiple printheads; and a shroud (12) surrounding the printheads and having a perimeter that conforms to the perimeter of the module (26), each printhead exposed through an opening in the shroud (12) so that fluid may be dispensed from the printheads past the shroud (12);

characterized in that the shroud is comprising a ridge (64, 66, 68, 70, 76) protruding along an exterior surface of the shroud (12) in front of openings (54) with respect a direction in which print media (16) is intended to move past printhead assembly modules (26) to block print media (16) from contacting the exposed part of the printheads during printing and end ridges (68, 70) which snake along each end of the exterior surface of the shroud (12).
The printhead assembly module of Claim 14, wherein each printhead protrudes a first distance through an opening in the shroud (12) and the ridge (64, 66, 68, 70, 76) protrudes from the shroud (12) a second distance greater than the first distance.